/*
 * Copyright 2009 Tran Nhut Trung.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); 
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, 
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 */
package org.eclipse.core.databinding.observable.gwt.internal;

import com.google.gwt.event.logical.shared.HasValueChangeHandlers;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.Command;
import com.google.gwt.user.client.DeferredCommand;
import com.google.gwt.user.client.ui.UIObject;
import com.google.gwt.user.client.ui.Widget;

import org.eclipse.core.databinding.observable.Diffs;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.gwt.AbstractWidgetObservableValue;
import org.eclipse.core.databinding.observable.gwt.IWidgetObservable;

public class WidgetPropertyObservableValue extends AbstractWidgetObservableValue implements IWidgetObservable {
  private UIObject widget;
  private String propName;
  protected boolean updating = false;
  protected Object oldValue;
  
  private ValueChangeHandler valueChangeHandler = new ValueChangeHandler(){
    public void onValueChange(ValueChangeEvent event) {
      // processUpdate(widget.getElement().getPropertyString(propName));
      processUpdate("" + event.getValue());
    }
  };
  private HandlerRegistration valueChangeHandlerRegistration;

  public WidgetPropertyObservableValue(UIObject widget, String propName) {
    this(Realm.getDefault(), widget, propName);
  }
  
  public WidgetPropertyObservableValue(Realm realm, UIObject widget, String propName) {
    super(realm, widget);
    
    this.widget = widget;
    this.propName = propName;
    
    /*
    DeferredCommand.addCommand(new Command(){
      public void execute() {
        oldValue = doGetValue();
      }
    });
    */
    // oldValue = doGetValue();
    
    if (widget instanceof HasValueChangeHandlers){
      // TODO: Do we need this?
      // valueChangeHandlerRegistration = ((HasValueChangeHandlers)widget).addValueChangeHandler(valueChangeHandler);
    }
  }
  
  public synchronized void dispose() {
    super.dispose();
    valueChangeHandlerRegistration.removeHandler();
  }

  protected void doSetApprovedValue(Object value) {
    if (widget == null){
      return;
    }
    
    try {
      updating = true;
      
      // Special case for UIObject
      if ("title".equals(propName)){
        widget.setTitle((String)value);
      }
      if ("visible".equals(propName)){
        widget.setVisible("true".equals(value));
      }
      if ("width".equals(propName)){
        widget.setWidth((String)value);
      }
      if ("height".equals(propName)){
        widget.setHeight((String)value);
      }
      if ("styleName".equals(propName)){
        widget.setStyleName((String)value);
      }
      if ("stylePrimaryName".equals(propName)){
        widget.setStylePrimaryName((String)value);
      }
      
      widget.getElement().setPropertyString(propName, value==null? "" : (String)value);
      // oldValue = widget.getElement().getPropertyString(propName);
      oldValue = doGetValue();
    } finally {
      updating = false;
    }
  }

  public Object doGetValue() {
    if (widget == null){
      return null;
    }
    
    if ("title".equals(propName)){
      return widget.getTitle();
    }
    if ("visible".equals(propName)){
      return widget.isVisible();
    }
    if ("styleName".equals(propName)){
      return widget.getStyleName();
    }
    if ("stylePrimaryName".equals(propName)){
      return widget.getStylePrimaryName();
    }

    return widget.getElement().getPropertyString(propName);
  }

  public Object getValueType() {
    return String.class;
  }

  protected void processUpdate(Object newValue){
    if (!updating) {
      if (!newValue.equals(oldValue)){
        fireValueChange(Diffs.createValueDiff(oldValue, newValue));
        oldValue = newValue;
      }
    }
  }
}
